Apparatus for testing holding capacity of sheet material

ABSTRACT

An apparatus for piercing sheet material and forming an elongated slot therein after which the apparatus is turned substantially 90* and a reverse force is applied to the apparatus to test the holding capacity of the sheet material. If the holding capacity exceeds a predetermined value, the apparatus tears the sheet material in a direction normal to the slot and the apparatus is removed from the material. If the holding capacity of the sheet material does not exceed the predetermined value, such sheet material is removed.

United States Patent Hallock, Jr.

[ Feb. 26, 1974 APPARATUS FOR TESTING HOLDING CAPACITY OF SHEET MATERIAL Robert L. l-lallock, Jr., 48 Rockland Ave., Larchmont, NY. 10538 Filed: Mar. 9, 1973 Appl. N0.: 339,789

Inventor:

US. Cl. 73/102 Int. Cl. G01n 3/00 Field of Search.. 73/102; 30/168, 367; 81/347,

References Cited UNITED STATES PATENTS 5/1905 Curtis ..8l/3.49 2/1884 Doersch ..8l/3.49

Primary Examiner-Jerry W. Myracle Attorney, Agent, or FirmA. Yates Dowell, Jr.

[ 5 7 ABSTRACT An apparatus for piercing sheet material and forming an elongated slot therein after which the apparatus is turned substantially 90 and a reverse force is applied to the apparatus to test the holding capacity of the sheet material. If the holding capacity exceeds a predetermined value, the apparatus tears the sheet material in a direction normal to the slot and the apparatus is removed from the material. If the holding capacity of the sheet material does not exceed the predetermined value, such sheet material is removed.

4 Claims, 6 Drawing Figures APPARATUS FOR TESTING HOLDING CAPACITY OF SHEET MATERIAL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to test equipment of various kinds and relates particularly to apparatus for testing the holding capacity of one material associated with another material.

2. Description of the Prior Art Heretofore the testing of sheet material such as a patch covering an opening in a base material normally has been accomplished by applying a force to the reverse side of the patch and measuring the force required to unseat the patch from the base material. In instances where the reverse sides of the material and the patch are not accessible, vacuum type implements have been provided which exert an outward force on the patch material. In some cases, an opening has been provided in the patch material after which an expanding head anchor bolt has been inserted through the hole in such a manner that the expanding head would engage the opposite side of the patch so that a reverse force could be applied.

In a particular application of the present device, the building industry at times uses a lightweight insulating deck or roof to form a base having sufficient strength to support build-up roofing materials. In this example, expanded vermiculite, perlite and similar materials are combined with cement in a ratio of approximately 6 to 1 and such materials are mixed together with sufficient water to produce a relatively thick flowable slurry which is pumped onto the roof support structure and permitted to set up and harden. It is desirable to place a protective covering on the lightweight insulating material as soon as such material has reached a minimum compressive strength sufficient to support the roof material as well as the workman who must apply the same. Ideally lightweight insulating material is tested with a conventional penetrometer; however, in actual practice the material normally is tested by a workman applying a reverse kick to the material so that the heel of his shoe makes an identation in the material. If the identation is relatively deep, it is assumed that the material is not sufficiently hard and therefore the application of the roofing material is postponed.

Preferably felt building paper or other covering material is applied to the lightweight insulating material as soon as such material has attained the minimum compressive strength to protect the material from the elements until the final roofing material is applied as well as to provide a base for the final roofing material. A hollow sheet metal nail such as that illustrated in US. Pat. No. 3,710,692 has been found satisfactory for attaching the covering material to the lightweight material; however, the lightweight material should be tested for strength before the covering material is applied. The lightweight material can be tested by driving a sheet metal nail into the lightweight material and then withdrawing the nail while measuring the force required to remove the same. However, since the head of the nail is flush with the lightweight material, it has been difficult to measure the holding capacity of such nail.

SUMMARY OF THE INVENTION The present invention is an apparatus for testing the holding capacity of sheet material such as a sheet metal nail having portions driven into, imbedded in, or otherwise attached to another material. The apparatus includes a tool having an elongated head with an enlarged penetrating portion adjacent to one end and spaced surfaces tapering inwardly and upwardly to a neck which is substantially circular in cross-section. The apparatus is caused to penetrate sheet material so that the enlarged area produces an elongated slot and the neck is located adjacent to the sheet material after which the apparatus is rotated and a reverse force is applied thereto. When the holding capacity of the sheet material is a predetermined value, the inwardly tapered surfaces of the head apply sheer forces to the sides of the slot and tear or cut the material so that the apparatus is extracted. If the holding capacity is less than the predetermined value, the sheet material is removed.

It is an object of the invention to provide a tool which is caused to penetrate sheet material and which is released therefrom when a predetermined force is applied.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective illustrating the tool of the present invention.

FIG. 2 is an enlarged fragmentary plan view of the head of the tool.

FIG. 3 is a side elevation thereof.

FIG. 4 is a fragmentary perspective illustrating one application of the invention.

FIG. 5 is an enlarged section on the line 55 of FIG. 4.

FIG. 6 is an enlarged fragmentary perspective illustrating the use of the tool with a strip of sheet material.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawing, a sheet material member 10, such as the head 11 of a sheet metal nail 12 (FIG. 4), or a strip of sheet material 13 (FIG. 6) is associated with another member 14 such as lightweight insulating roofing material or the like.

In order to test the holding capacity of the sheet material member 10, a tool 15 is provided having a substantially flat head 16 connected by a generally cylindrical neck 17 to a body 18. The body 18 is of generally T-shaped configuration and includes an upper cross piece 19 integrally connected to a downwardly extending stem 20 terminating in a shoulder 21 adjacent to the neck 17. A pair of finger receiving recesses 22 are provided in the lower edges of the cross piece 19 and a flattened driving portion 23 is provided on the upper edge thereof. The driving portion 23 is adapted to be struck by an impact tool such as a hammer or the like to cause the head 16 to penetrate the sheet material member 10.

The head 16 is of a constant thickness throughout its length, and such thickness corresponds generally to the diameter of the cylindrical neck 17. A chisel-shaped penetrating point 24 is provided at the end of the head 16 remote from the neck 17. A pair of lower sides 25 extend upwardly and outwardly from the penetrating point 24 to corners 26 located outwardly of the neck 17 to provide an enlarged portion having a width greater than the thickness of the head. From the corners 26, a pair of upper sides 27 extend upwardly and inwardly to a position substantially tangential with the cylindrical neck 17. The head 16 is of sufficient length that the upper sides 27 are disposed at a slight angle relative to a vertical plane.

As an example, a tool having a head 16 with a length of approximately 0.5 inch and a thickness of approximately 0.120 inch may have the opposed corners 26 spaced apart a distance substantially 0.135 inch. In this example, the neck 17 has a diameter of .120 inch or slightly less. This tool is for use with a sheet metal nail constructed of half hard galvanized sheet steel having a thickness of approximately 0.0012 inch.

In the operation of the device, the penetrating point 24 of the head is placed in a desired position on the member after which the driving portion 23 is struck with an impact tool (not shown) to cause the head to pierce the sheet material member and form a generally rectangular slot 28 while bending tabs 29 downwardly at each end of the slot. The head penetrates until the shoulder 21 engages the sheet material and resists further penetration. In this position, the generally cylindrical neck 17 is in alignment with the slot 28. The tool then is rotated substantially 90 after which the operator places his fingers in the recesses 22 and applies a slow even pull in an upward direction. The upper sides 27 engage the sides of the slot 28 and during the initial upward movement most of the force applied to the sheet material is a compression force due to the small taper of the upper sides 27. Continued upward movement increases the sheer forces on the sheet material so that unless the sheet material is released from the member to which it is attached, the upper sides will cut opposed tabs 30 in the sheet material at opposite sides of the slot 28 to release the head 16 of the tool.

The force required to pull the head of the tool through the sheet material is controlled by the thickness and strength of the sheet material, the angularity of the upper sides 27 of the head 16, and the width between the corners 26.

In the specific embodiment mentioned, an upward force of approximately 35 pounds is required for the head to cut the tabs 30 and release the head. Therefore, if the holding capacity of the nail 12 is less than 35 pounds, the nail is released from the material 14 and is withdrawn therefrom by the tool 15. On the other hand, if the holding capacity of the nail is greater than 35 pounds, then the nail remains fixed and releases the head 16 of the tool. It has been found that a nail having a holding capacity of 35 pounds or more indicates that the lightweight insulating material has attained the minimum compressive strength required to support the roofing material and the workman who applies the same.

I claim:

1. A tool for testing the holding capacity of sheet material connected to another member, said tool comprising a body having a driving portion at one end, a head connected to the opposite end of said body by a neck having a predetermined width and thickness, said head having a penetrating point at the end remote from said neck, a pair of lower sides extending upwardly and outwardly from said penetrating point and terminating at opposed comers, said corners being spaced apart a distance greater than the width of said neck, a pair of upper sides extending from said comers upwardly and inwardly to a position adjacent to said neck, and the thickness of said head being substantially equal to the thickness of said neck, whereby penetration of said head into sheet material cuts an elongated slot so that I when the tool is rotated substantially 21 predetermined force is required to pull the head through the slot.

2. The structure of claim 1 in which said body includes shoulder means to limit the penetration of said head.

3. The structure of claim 1 in which said upper sides are disposed at a slight angle to a vertical plane.

4. A tool for testing the holding capacity of sheet material connected to another member, said tool comprising a generally T-shaped body having an upper cross piece and a downwardly depending stem, a driving portion disposed generally centrally of the upper edge of said cross piece, a finger receiving recess in the lower edge of said cross piece on each side of said stem, a substantially cylindrical neck connected to the end of said stem remote from said cross piece, a substantially flat head connected to said neck in spaced relationship to said stem, said head having a penetrating point at the end remote from said neck, a pair of lower sides extending upwardly and outwardly from said penetrating point and terminating in opposed corners, said corners being spaced apart a distance greater than the diameter of said neck, a pair of upper sides extending from said corners upwardly and inwardly to the periphery of said neck, and the thickness of said head being substantially equal to the diameter of said neck, whereby penetration of said head into sheet material cuts an elongated slot so that the tool can be rotated substantially 90 when the sheet material is adjacent to said neck after which an upward pull is applied by the fingers of an operator to either remove the sheet material from the other member or pull the head through the slot. 

1. A tool for testing the holding capacity of sheet material connected to another member, said tool comprising a body having a driving portion at one end, a head connected to the opposite end of said body by a neck having a predetermined width and thickness, said head having a penetrating point at the end remote from said neck, a pair of lower sides extending upwardly and outwardly from said penetrating point and terminating at opposed corners, said corners being spaced apart a distance greater than the width of said neck, a pair of upper sides extending from said corners upwardly and inwardly to a position adjacent to said neck, and the thickness of said head being substantially equal to the thickness of said neck, whereby penetration of said head into sheet material cuts an elongated slot so that when the tool is rotated substantially 90* a predetermined force is required to pull the head through the slot.
 2. The structure of claim 1 in which said body includes shoulder means to limit the penetration of said head.
 3. The structure of claim 1 in which said upper sides are disposed at a slight angle to a vertical plane.
 4. A tool for testing the holding capacity of sheet material connected to another member, said tool comprising a generally T-shaped body having an upper cross piece and a downwardly depending stem, a driving portion disposed generally centrally of the upper edge of said cross piece, a finger receiving recess in the lower edge of said cross piece on each side of said stem, a substantially cylindrical neck connected to the end of said stem remote from said cross piece, a substantially flat head connected to said neck in spaced relationship to said stem, said head having a penetrating point at the end remote from said neck, a pair of lower sides eXtending upwardly and outwardly from said penetrating point and terminating in opposed corners, said corners being spaced apart a distance greater than the diameter of said neck, a pair of upper sides extending from said corners upwardly and inwardly to the periphery of said neck, and the thickness of said head being substantially equal to the diameter of said neck, whereby penetration of said head into sheet material cuts an elongated slot so that the tool can be rotated substantially 90* when the sheet material is adjacent to said neck after which an upward pull is applied by the fingers of an operator to either remove the sheet material from the other member or pull the head through the slot. 